It states to select ph 7 buffer for general testing or ph 4 or 10 if I'm measuring acidic/basic samples. Theres only one calibration point and it's made by Eutech/Oakton and it's a waterproof phtestr-1 I'm using an ebb/flow system so what buffer solution do I need? I sorry but I know jack about all this and I'm learnig from this forum.